‘Valley Gold’ is a hybrid of Citrus reticulata variety Ellendale (not patented) (the seed parent) and an unpatented mandarin hybrid variety Robin (not patented) (the pollen parent). In 1980, pollen from ‘Robin’ was applied by hand to the stigmas of ‘Ellendale’. The resulting fruits were collected in June 1981 whereafter seeds from each fruit were extracted and irradiated and thereafter planted in 1982. The resulting 73 seedlings were transplanted to a breeding orchard situated in Addo, in the Eastern Cape province of the Republic of South Africa (global positioning satellite co-ordinates 25°42′E; 33°34′S). These seedlings were not grafted and were grown on their own roots. Due to the so-called juvenility phenomenon in citrus trees as is known in the art, trees resulting from these transplanted seedlings only bore fruit in 1992. These trees were then evaluated for fruit quality traits. Based on the results of this evaluation, six of the aforementioned trees were selected for further evaluation, of which one of these selections resulted in the present ‘Valley Gold’ variety. Valley Gold was made subject of a South African Plant Breeders' Rights application in January 2000. This application was subsequently granted in 2004 under number ZA 20043214.
Fruit quality, and the time of fruit maturity (mid to end July), makes this selection a good candidate for the European market.
Severe to mild fruit splitting may occur in March or April, depending on rind thickness. However, crop load is still acceptable after split fruit has been dropped. Additionally, trees tend to be alternate-bearing.
‘Valley Gold’ was first asexually propagated in Addo, South Africa in 1995 when buds were collected from a hybrid seedling designated X83-2505/5, and then budded onto ‘Carizzo citrange’ rootstocks. Ten trees of ‘Valley Gold’ were planted in the field in September 1996 for description purposes. All characteristics of the original tree and its fruit as determined and described appear to be transmitted through succeeding asexual propagations. While ‘Valley Gold’ has been propagated and grown on ‘Carizzo citrange’ rootstock, no incompatibility or other rootstock related problems have been observed. The mother tree is growing on its own roots and is currently (2008) 24 years old. Although the tree condition is beginning to decline, the fruit quality is and always has been good.
Further, ‘Valley Gold’ has been cleansed of all viruses and viroids by shoot-tip grafting (STG), followed by pre-immunization with Citrus tristeza virus LMS6. This was done through a regulated process, which involves taking vegetative buds from the mother tree and introducing same into the South African Citrus Improvement Scheme. In this process, plant material is shoot-tip grafted to provide a virus-free source of bud wood material. Material so obtained is then pre-immunized with a mild strain of the aforementioned Citrus tristeza virus, followed by a certification by the Citrus Foundation Block.
The applicant is aware of U.S. Plant Pat. No. 16,289 ('289). The present variety is distinguishable over '289 in that, inter alia, not only is the present variety diploid whereas '289 is triploid, but also the respective rind colors differ.